- Pope Honorius I (Papacy: 625-638): viewed Islam as Arianism. Allegedly committed heresy of Monothelitism.
- Pope Formosus (Papacy: 891-896): Cadaver Synod: where his body as exhumed for the trial of stirring distrust in Bulgaria against other popes: Pope Nicholas I, Pope John VIII.
- Pope John VI (Papacy: 896-897): Instigated the Cadaver Synod, which ultimately led to his downfall and death.
- Pope John XII (Papacy: 955-964): Accused of gambling, incest, and killed by jealous husband while enjoying adultery.
- Pope John XXII (Papacy: 1316-1334): Canonized Thomas Aquinas. Controversially believed that the blessed would not see God's presence immediately after death, but would have to wait until the Last Judgement, which was considered heretical by most theologians and ultimately led him to retract his position before his death; his successor, Pope Benedict XII, officially clarified the Church teaching that the blessed immediately experience the Beatific Vision after death.
The above list was from the Youtube video above.